Hi,
We have samba4 DC running @ remote office and connected to HO through IPSec tunnel, all will work well when there connectivity to all DCs, but when 1 DC is unreachable, all other location DCs are not allowing users to login. It says "trust relationship between this workstation and domain controller failed". Can you please help me in this ?
Thanks,
Vijay

Use Samba 4.3 and set kccsrv:samba_kcc=yes (now on by default in 4.5.0rc1) and then define site links between your sites, so that replication is correctly matched the hub-and-spoke topology of your network.